Torque limiting coupling

Abstract

A torque limiting coupling, in drive lines or driving agricultural machinery has a first coupling part (1) and a second coupling part (14), as well as a switching ring (19) loaded by a spring (28). Balls (30) transmit torque between the first coupling part (1) and the second coupling part (14). The balls are axially adjustable in apertures (6) of the first coupling part (1). The apertures (6) are uniformly circumferentially distributed around the axis of rotation (2). In the torque transmitting position, the apertures (6) are positioned opposite torque transmitting recesses (16) in the second coupling part (14). The balls (30) are held in recesses (16) in the engaged condition by the switching ring (19). When the torque is exceeded, the balls (30) escape out of the torque transmitting recesses (16). In the course of this process, the switching ring (19) is first displaced against the force of the loading spring (28). To ensure that the coupling is transferred only when the first coupling part (1) is associated in a certain way with the second coupling part (14), a control ball (31) is provided which cooperates with a first control recess (21) of the second coupling part (14).

I claim: 
     
       1. A torque limiting coupling, used in drives of or for driving agricultural machinery, comprising: a first coupling part with apertures which extend parallel to an axis of rotation, said apertures being uniformly distributed on a rolling circle;   a second coupling part rotatably supported on said first coupling part, said second coupling part at its end face opposed to a first exit end of the apertures, including torque transmitting recesses arranged to match said apertures;   a switching ring rotatably arranged around the axis of rotation relative to the first coupling part;   freewheeling recesses are in said switching ring in its end face opposed to a second exit end of the apertures;   the freewheeling recesses are arranged to match the first coupling part aperture distribution on the rolling circle and in a torque transmitting position, the switching ring being held in a desired rotational position around the axis of rotation relative to the first coupling part, such that the freewheeling recesses are held so as to be displaced in the circumferential direction relative to the apertures;   torque transmitting balls are axially adjustably received in the apertures, the torque transmitting balls engage the torque transmitting recesses in the torque transmitting position and the freewheeling recesses in the freewheeling position; and   a spring axially acting on the switching ring, said spring supports said ring against any adjustment away from the apertures, said first coupling part including an axially extending control aperture arranged relative to the rotational axis on a control circle whose diameter deviates from that of the rolling circle, a first control recess and second control recess are arranged opposite the exit ends of the control aperture in the end faces of the second coupling part and switching ring, respectively, the second control recess being associated with the switching ring and being circumferentially offset in accordance with the freewheeling recesses in the torque transmitting position; and   a control ball received in the control aperture to engage either the first or the second control recess with the control ball being adjustable parallel to the axis of rotation.   
     
     
       2. A torque limiting coupling according to claim 1, wherein the control circle includes a smaller diameter than the rolling circle. 
     
     
       3. A torque limiting coupling according to claim 1, wherein the control ball has a smaller diameter than the torque transmitting balls, the torque transmitting recesses at the second coupling part end face, the first control recess at the second coupling Part end face, the freewheeling recesses at the switching ring end face, as well as the second control recess at the switching ring end face, and the apertures, and the control aperture, having the same diameter.